#include"string.h"
#define _CRT_SECURE_NO_WARNINGS 1
namespace xg
{
	const size_t string::npos = -1;
	void string::reserve(size_t n)
	{
		if (n > _capacity)
		{
			char* tmp = new char[n+1];
			strcpy(tmp, _str);
			delete[] _str;

			_str = tmp;
			_capacity = n;

		}
	}
	void string::push_back(char ch)
	{
		if (_size == _capacity)
		{
			/*int newcapacity = _capacity == 0 ? 4:2 * _capacity;
			char* tmp = new char[2 * newcapacity];
			strcpy(tmp, _str);
			delete[] _str;
			_str = tmp;
			_capacity = newcapacity;*/
			reserve(_capacity==0?4:2*_capacity);
		}
		_str[_size] = ch;
		++_size;
		_str[_size] = '\0';
	}
	string& string::operator+=(char ch)
	{
		push_back(ch);
		return *this;
	}
	void string::append(const char* s)
	{
		int len = strlen(s);
		if (len + _size > _capacity)
		{
				reserve(_size + len > 2 * _capacity ? _size + len : 2 * _capacity);
		}
		strcpy(_str + _size, s);
		_size += len;
	}
	string& string::operator+=(const char* s)
	{
		append(s);
		return *this;
	}
	void string::insert(size_t pos, char ch)
	{
		assert(pos < _size);
		if (_size == _capacity)
		{
			reserve(2 * _capacity);
		}
		size_t end = _size+1;
		while (end > pos)
		{
			_str[end ] = _str[end-1];
			end--;
		}
		_str[pos] = ch;
		_size++;
	}
	void string::insert(size_t pos, const char* s)
	{
		size_t len = strlen(s);
		if (_size + len > _capacity)
		{
			reserve(2 * _capacity);
		}
		size_t end = _size + len;
		while (end - len > pos)
		{
			_str[end] = _str[end - 1];
		}
		strcpy(_str + len, s);
		_size += len;
	}
	void string::erase(size_t pos, int len)
	{
		assert(pos < _size);
		if (len + pos >= _size)
		{
			for (int i = pos; i <=_size; i++)
			{
				_str[pos] = '\0';
				_size = pos;
			}
		}
		else
		{
			for (int i = pos + len; i <= _size; i++)
			{
				_str[i - len] = _str[i];
			}
			_size -= len;
		}
	}
	size_t string::find(char ch, size_t pos)
	{
		assert(pos < _size);
		for (int i = pos; i < _size; i++)
		{
			if (_str[i] == ch)
				return i;
		}
		return npos;
	}
	size_t string::find(const char* s, size_t pos)
	{
		assert(pos < _size);
		char* ptr = strstr(_str + pos, s);
		if (ptr == nullptr)
			return npos;
		else
			return ptr - _str;
	}
	string string::substr(size_t pos, size_t len)
	{
		assert(pos < _size);
		if (pos + len > _size)
			len = _size - pos;
		string sub;

		sub.reserve(len);
		for (size_t i = 0; i < len; i++)
		{
			sub += _str[i+pos];
		}
		return sub;
	}
	bool operator<(const string& s1, const string& s2)
	{
		return strcmp(s1.c_str(), s2.c_str()) < 0;
	}
	bool operator==(const string& s1, const string& s2)
	{
		return strcmp(s1.c_str(), s2.c_str()) == 0;
	}

	bool operator<=(const string& s1, const string& s2)
	{
		return s1 < s2 || s1 == s2;
	}

	bool operator>(const string& s1, const string& s2)
	{
		return !(s1 <= s2);
	}

	bool operator>=(const string& s1, const string& s2)
	{
		return !(s1 < s2);
	}

	

	bool operator!=(const string& s1, const string& s2)
	{
		return !(s1 == s2);
	}
	ostream& operator<<(ostream& out, const string& s)
	{
		for (auto ch : s)
		{
			out << ch;
		}

		return out;
	}
	istream& operator>>(istream& in, string& s)
	{
		s.clear();
		const int N = 256;
		int i = 0;
		char buff[N];
		char ch;
		ch = in.get();
		while (ch != ' ' && ch != '\n')
		{
			buff[i++] = ch;
			if (i == N - 1)
			{
				buff[i] = '\0';
				s += buff;

				i = 0;
			}
			ch = in.get();
		}
		if (i > 0)
		{
			buff[i] = '\0';
			s += buff;
		}

		return in;
	}

}
